The present invention relates to a method of measuring the rate of oxidation on the surface of a metal melt, especially a melt of aluminum or of an aluminum alloy.
The oxidation behavior of metal melts can be strongly influenced by dissolved metallic elements, which can be present as impurities and/or alloying components. For example, the presence of lithium or magnesium in an aluminum melt leads to an increase in the rate of oxidation.
In foundries, the oxidation of metal melts is made apparent by the formation of dross. Dross formation can become a significant cost factor as a consequence of the loss of metal which occurs. Therefore, efforts are being made to reduce the quantity of dross to a minimum. The formation of dross is decisively influenced by the rate of oxidation of the metal melt, that is, the speed with which an oxide skin forms.
The measurement of the rate of oxidation of a metal melt is usually carried out as follows: the oxide skin is removed from the melt surface at different intervals of time and, after dissolving out the metallic components, is filtered, roasted, weighed out and analyzed.
In light of the foregoing it would be highly desirable to provide a method for measuring the rate of oxidation at the surface of a metal melt and also determine the concentration in the metal melt of the elements influencing the rate of oxidation in a simple manner.